The present invention relates to a magnetic tape medium for storing data, to write heads for writing a servo pattern to a magnetic tape medium, and to methods for writing a servo pattern to a magnetic tape medium.
Magnetic tape storage media typically comprise servo information prerecorded in one or more of dedicated servo bands that extend next to data tracks for storing data, which servo bands extend in a longitudinal direction along the tape medium. A servo band typically is read by a dedicated servo reader of a tape head of a tape drive, into which a cartridge containing the tape medium is inserted to. The read servo information allows for determining a lateral deviation of the tape medium from a lateral reference position, which lateral reference position is desired for correctly reading data from and writing data to the tape medium by dedicated read and write elements of the tape head. A position error signal supplied by the servo reader may be translated into a control signal for an actuator for controlling the lateral position of the tape head with respect to the tape medium.
Timing-based servo (TBS) is a technology developed specifically for linear tape drives in the late '90s. In TBS systems, recorded servo patterns comprise transitions with at least two different azimuthal slopes. The tape head lateral position is derived from the relative timing of pulses generated by a servo reader reading the servo pattern. TBS was adopted by the linear tape open (LTO) consortium, and a complete format for LTO tape drives of the first generation was standardized by the European Computer Manufacturers Association (ECMA) in 2001 as ECMA-319. The servo patterns in LTO are written on five dedicated servo bands that straddle four data bands.